Are the behavioral immune system and pathogen disgust identical?

Abstract

Pathogen disgust evolved as a psychological adaptation in response to the recurring selective pressures posed by disease-causing organisms. Recently, social psychologists taking an evolutionary perspective have posited the existence of a behavioral immune system, which purportedly evolved for the same reason. However, researchers using the concept of the behavioral immune system curiously claim it is not identical to pathogen disgust. Here, we argue that despite different names, pathogen disgust and the behavioral immune system are indeed functionally and computationally the same. We provide two reasons why they are treated as distinct, or at least nonidentical, systems. The first relates to how emotions are defined in different academic disciplines. The second relates to common intuitions regarding the distinction between emotion and cognition. We suggest that if researchers focus on the level of information processing and develop computational models of the adaptation in question—pathogen avoidance or otherwise—problems introduced by historical definitions and folk intuitions are more likely to disappear.